Contact construction



May 21, 1957 J J i s 2,793,267

CONTACT CONSTRUCTION Filed Sept. 29, 1955 2 Sheets-Sheet 1 W 5/ I: W

2 Shets-Sheet 2 Filed Sept. 29, 1 955 Unired States Patent "ice CONTACTCONSTRUCTION JohnJ. Mikos, Highland Park, lll., assignor to S & C

Electric Company, Chicago, 111., a corporation of Delaware Thisinvention relates, generally, to the construction of electrical contactsand it has particular relation to the construction of line contacts foruse in the housing of a bayonet type fuse cutout. It constitutes animprovement over the contact construction shown in U. S. Patent No.2,591,949, issued April 8, 1952.

The bayonet type fuse cutout of the above patent employs a tubularporcelain housing provided with a line terminal contact assembly at eachend for engagement by terminals of a fuse tube. Each such contactassembly includes a cylindrical contact sleeve and a surroundingretainer sleeve to which a line conductor fitting is secured. The latterhas a cylindrical opening therethrough in alignment with openings in theporcelain housing through which line conductors can be inserted to beheld in place by set screws extending transversely of the cylindricalopening in the line conductor fitting.

As a result of increase in load applied to this type of cutout and theuse of aluminum line conductors in addition to copper, it has been foundthat there should be an increase in the area of contact engagement withthe line conductors in order to reduce heating and increase the usefullife of the device. Because of space limitations imposed by theporcelain housing, it has not been feasible merely to increase the sizeof the line conductor fittings and employ a larger number of set screwsfor clamping the line conductors in place. Other means were developed aswill appear hereinafter.

Among the objects of this invention are: To increase the currentcarrying ability of the line terminal contact assemblies of a bayonettype fuse cutout without increasing the size of the porcelain housing onwhich such assemblies are mounted; to increase substantially the area ofcontact engagement with the line conductors; to receive difierentdiameters of line conductor at the same time; to employ pressure bar'soperated by pressure bolts for contacting the line conductors andclamping them in place in the line contact assemblies; to accommodateboth copper and aluminum line conductors; to provide a universalconnection between the pressure bar and the pressure bolt associatedtherewith; to form the universal connection by heading over the innerend of a pressure bolt within its pressure bar while permitting freedomof movement therebetween; to provide the universal connection byemploying a pair of roll pins in a pressure bar to interengage a neckeddown inner end of its pressure bolt; and to form the terminal lugcarrying the pressure bars and pressure bolts integrally with theretainer sleeve.

Other objects of this invention will, in part, be obvious and in partappear hereinafter.

This invention is disclosed in the embodiments thereof shown in theaccompanying drawings and it comprises the features of construction,combination of elements and arrangement of parts that will beexemplified in the constructions hereinafter set forth and the scope ofthe application of which will be indicated in the appended claims.

Fateiited May 21, 1957 For a more complete understanding of the natureand scope of this invention reference can be had to the followingdetailed description, taken together with the accompanying drawings, inwhich:

Figure 1 is a view in side elevation of a bayonet type fuse cutout inwhich the present invention is embodied;

Figure 2 is a view, partly in side elevation and partly in verticalsection, showing the application of one embodiment of the invention to abayonet type fuse cutout;

Figure 3 is a view, partly in vertical section and partly in sideelevation, showing in further detail how the first embodiment of theinvention is employed in the cutout housing;

Figure 4 is a vertical sectional view of the fuse which forms theprincipal part of the bayonet member that is inserted in the housingshown in Figure 3;

Figure 5 is a horizontal sectional view taken generally along the line5-5 of Figure 3 and showing only the lower line terminal assembly;

Figure 6 is a view, taken generally along the line 6-6 of Figure 3, andshowing only details of construction of the lower line terminalassembly;

Figure 7 is a view, in side elevation, of one of the terminal lugassemblies;

Figure 8 is a longitudinal sectional view of a higher ampere ratinghousing for use with line terminal assemblies having a higher ampererating than that for which the construction shown in the precedingfigures is adapted;

Figure 9 is a horizontal sectional View taken generally along the line99 of Figure 8 and showing only details of construction of the lowerline terminal assemy;

Figure 10 is a vertical sectional view taken generally along the line1010 of Figure 8 and showing only details of construction of the lowerline terminal assembly; and

Figure 11 is a vertical sectional view taken generally along the line11--11 of Figure 10.

Referring first to the embodiment of the invention illustrated inFigures 1-7 and particularly to Figure 1. it will be observed that thereference character 10 designates, generally, a bayonet type fuse cutoutconstructed generally as disclosed in the above mentioned patent. Thecutout 10 is arranged to be mounted on a cross arm 11, or the like, by aclamp bracket, shown generally at 12. The clamp bracket 12 is connectedby an intermediate bracket 13 to a mounting bracket 14 which surroundsthe central portion of a tubular porcelain housing 15 which iscorrugated to provide increased creepage distance over its externalsurface as is well understood. Near the ends of the porcelain housing 15are upper and lower line conductor openings 16 and 17 which extendtransversely through the housing and permit the insertion of conductorsfrom either side.

As shown in Figures 2, 3 and 4 of the drawings a handle 18 is mounted atthe upper end of a bayonet type fuse, shown generally at 19, that isarranged to be inserted in the porcelain housing. The bayonet type fuse19 is provided with upper and lower cylindrical contacts 20 and 21 atthe ends of a fuse tube 22. The upper cylindrical contact 20 is threadedat 23 for receiving the handle 18. Within the fuse tube 22 i a springand cable assembly, shown generally at 24, which extends from the uppercylindrical contact 20 and has a fuse link 25 connected thereto at itslower end. The fuse link 25 has a cone terminal 26 which engages atubular projection 27 can semi-circular extension 28 from the lowercylindrical contact 21. The upper and lower cylindrical contacts 20 and21 on the fuse tube 22 are arranged to have contact engagement withupper and lower line terminal assemblies 30 and 31 which are mounted atthe respective ends of the porcelain housing 15, as shown more clearlyin Figures 2 and 3 of the drawings. These line terminal assemblies 30and 31 are provided with cylindrical contact sleeves 32 and 33 that arearranged to engage directly with the cylindrical contacts 20 and 21.Surrounding the contact sleeves 32 and 33 are cylindrical retainersleeves 34 and 35 which are secured by cement 36 and 37 to therespective ends of the porcelain housing 15 as described in more detailin the patent above referred to. An insulating liner 38 in the form of asleeve of insulation is interposed between the upper and lower lineterminal assemblies 30 and 31 in order to protect the inner surface ofthe porcelain housing 15 from any are that might be drawn when thebayonet type fuse 19 is withdrawn under load and for assisting inextinguishing such arc.

It will be understood that the line terminal assemblies 30 and 31 arearranged to be connected to line conductors which are inserted throughline conductor openings 16 and 17 in the porcelain housing 15. Thepresent invention has to do particularly with the means for connectingthese line conductors to these line terminal assemblies in such manneras to provide increased contact engagement and to accommodate conductorsof aluminum as well as conductors of copper.

The details of the improved construction are illustrated more clearly inFigures 5, 6 and 7 of the drawings. As there shown a terminal lugassembly, indicated generally at 42, is provided. The same terminal lugassembly 42 is applied to both the upper and lower line terminalassemblies 30 and 31. Accordingly, it will be described only withreference to the lower line terminal assembly 31. The terminal lugassembly 42 comprises a terminal lug 43 that is formed preferably of analuminum bronze alloy by a shell molding process. This alloy has highstrength and is not subject to stress corrosion or to corrosioncracking. The shell molding process is used for reasons of economy,Sandcasting and subsequent machining can also be used but at a highercost.

After formation, the terminal lug 43 is tin plated to accommodatealuminum as well as copper conductors. The terminal lug 43 has anarcuate portion 44 which fits around the intermediate portion of thecylindrical retainer sleeves 34 or 35 as the case may be and is securedthereto by rivets 45 which project also through the cylindrical contactsleeves 32 or 33.

For receiving the line conductors the terminal lug 43 is provided withan oblong opening 46, Figure 7, which extends entirely therethrough andis positioned in alignment with the respective line conductor openings16 or 17. As seen in Figure 7 the lower end of the oblong opening 46 isflat as indicated at 47, while the upper end is formed by arcuatesurfaces 48 and 49. These surfaces have different radii as indicated at50 and 51. The smaller radius 50 for the surface 48 is located with thecenter above the center for the larger radius 51. This locates thearcuate surface 48 between portions of the arcuate surface 45 and thusprovides for receiving different diameters of conductors, such as theconductors 52 and 53, Figure 6, in intimate contact engagement. Forexample, the terminal lug assembly 42 is arranged to receive and provideintimate contact engagement with conductors ranging from a diameter of.128" to .328.

With a view to securing the conductors 52 and 53 in the respectiveterminal lug assembly 42 and providing intimate contact engagementtherewith pressure bar 54 are employed. These pressure bars are formedpreferably of copper and are tin covered preferably by hot tin dippingto accommodate aluminum as well as copper line conductors. The hot tindipping of the pressure bars provides a relatively thick film of tinover the copper pressure bars 54 which is not easily pierced and whichslides readily relative to the conductors because of the lubrieatingaction provided bythis method of coating. Each of the pressure bars 54has a concave surface 55 for overlying substantially a semi-circularportion of the respective conductor 52 or 53.

As shown in Figure 6 each pressure bar 54 has a small diameter opening56 on the side opposite the concave surface 55 provided with a shoulder57 connecting it with a large diameter opening 53. A neck portion 59 ofthe pressure bolt 69 extends through the small diameter opening 56 andit has a headed over portion 61 within the large diameter opening 58.The neck portion 59 is inserted through the small diameter opening 56and then a suitable peening tool is inserted through an opening 62 forheading over the portion 61 after the pressure bolt 60 has been threadedthrough a wall 63 which forms a part of the terminal lug 43. While theheaded over portion 61 prevents detachment of the pressure bar 54 fromthe pressure bolt 66 after assembly, the construction is such that thepressure bar 54 is relatively loosely mounted on the pressure bolt 69and thus a universal connection is provided therebetween which permitssome degree of freedom of movement between the pressure bar 54 and thepressure bolt 60.

In operation'it will be understood that conductors 52 and 53 ofdifferent diameters can be connected to each of the line terminalassemblies 35 and 31 as may be desired. Of course two conductors of thesame diameter can be so connected. In the event that only a singlecondoctor is to be connected to one or both of the line terminalassemblies 30 or 31 it would be inserted through the respective opening16 or 17 in the porcelain housing 15 and then between both of thepressure bars 54 and the arcuate surfaces 48 and 49 to the end that bothpressure bars 54 would have contact engagement therewith and thusprovide a relatively great area of contact engagement therewith. Theuniversal joint connections between the pressure bars 54 and therespective pressure bolts 60 permit the former to seat properly againstthe line conductor or conductors, as the case may be, and provideintimate contact engagement therewith.

In Figures 811 a higher ampere rating construction for the bayonet typefuse cutout is shown. Only the housing and line terminal contactassemblies are. illustrated, the bayonet member including the handle andthe.

fuse being generally similar to the handle 18 and the fuse 19 describedhereinbefore but of somewhat larger size.

As shown in Figure 8 a porcelain housing 65 is employed whichcorresponds to the porcelain housing 15 previously described. Theporcelain housing 65 is provided with corrugations between its ends forincreasing the creepage distance. Near its ends upper and lower lineterminal assemblies 66 and 67 are provided corresponding to the lineterminal assemblies 30 and 31 previously described. The line terminalassemblies 66 and 67 include cylindrical contact sleeves 68 and 69 thatare surrounded by cylindrical retainer sleeves 70 and 71. In thisinstance the cylindrical retainer sleeves 7t and 71 are formedintegrally with a terminal lug 72 by a.

shell molding process. Since the same construction is cracking or stresscorrosion. process was used for reasons of economy although sand castingand machining can be used. 1

As shown in Figure 11 an oblong opening 73 is provided through each ofthe terminal lugs 72 in alignment f with line conductor openings 74 and75 near the ends of the porcelain housing 65. As shown the upper andlower ends of the oblong openings 73 are generally semicircular.Movably'mounted within the oblong opening.

73 are two pressure bars 78 that are formed preferably of copper and aretin covered preferably by hot tin dipping in order to accommodatealuminum as well as copper line conductors as outlined herebefore forthe pressure bars 54. Each pressure bar 78 has a concave surface forengaging line conductors 80 and 31 which, as shown in Figure 10, can beof different diameters. For example conductors ranging in diameter from.162" to .447 can be accommodated.

The pressure bars 78 are moved into good contact engagement with one orboth of the line conductors by pressure bolts 82. The inner ends of thepressure bolts 82 are reduced in diameter as indicated at 83 and areprovided with necked down or annularly grooved portions 84 forprojecting into an opening 85 in the side of the respective pressurebars 78 opposite the concave surface 79 for interengagement with rollpins 86 which extend longitudinally of each pressure bar 78. Thepressure bolts 82 are threaded through a wall 87 of the terminal lug 72and then the pressure bars 75 are positioned on the reduced diameterends 83. Thereafter the roll pins 86 are inserted through the respectivepressure bars 78 to hold them inseparable with respect to the pressurebolts 82. At the same time a universal joint connection is providedtherebetween which permits some freedom of movement of each pressure bar78 with respect to its pressure bolt 82. This facilitates seatingagainst the line conductor and provides intimate contact engagementtherewith over a relatively large surface. At their outer ends thepressure bolts 82 can be provided with hexagonal heads 88 for receivinga socket Wrench and they also can be provided with slots 39 forreceiving a screw driver.

In operation it will be understood that two conductors of differentdiameters can be connected to each terminal lug 72 as shown in Figure10. Also two conductors of the same diameter can be so connected. In theevent that a single conductor is connected to the terminal lug 72, it ispositioned therein so that both of the pressure bars 78 can engage andclamp it in position.

Since certain further changes can be made in the foregoing constructionsand different embodiments of the invention can be made without departingfrom the spirit and scope thereof it is intended that all matter shownin the accompanying drawings and described hereinbefore .6 shall beinterpreted as illustrative and not in a limiting sense.

What is claimed as new is:

l. A contact construction for mounting at the end of a tubular porcelaininsulator or the like for receiving a cylindrical terminal of a bayonettype fuse and connecting the same to line conductors extending throughtransverse openings in said insulator, said contact constructioncomprising, in combination, cylindrical contact means for engaginginternally said cylindrical terminal and adapted externally to besecured in said insulator; and a terminal lug assembly including aterminal lug mounted externally on said cylindrical contact means andhaving a generally oblong opening therethroug'n aligned with saidopenings in said insulator, two pressure bars freely slidably mounted insaid oblong opening and each having a concave contact surface along oneside for engaging a conductor between it and the opposite side of saidoblong opening, and a pressure bolt threaded in said terminal lug andhaving a universal connection to each pressure bar for clamping saidconductor between said contact surface and said opposite side of saidoblong opening.

2. The invention, as set forth in claim 1, wherein the terminal lug istin plated and the pressure bar is hot tin dipped to accommodate copperand aluminum conductors.

3. The invention, as set forth in claim I, wherein the opposite side ofthe oblong opening is formed by two arcuate surfaces of different radiiwith the surface having the smaller radius being directly opposite theconcave contact surface on the pressure bar and intermediate twosections of the larger radius surface.

4. The invention, as set forth in claim 1, wherein the universalconnection between the pressure bar and the pressure bolt is formed by apair of roll pins extending in parallel spaced relation lengthwise ofthe former and interengaging a necked down portion on the latter.

References Cited in the file of this patent UNITED STATES PATENTS

